Two genetic stocks of chickens (Ottawa Randombred Control and Ottawa Selected) show a clear-cut reversal in dominance rank, relative to each other, when tested in pair contests at different ages. Extensive peck-order observations in 6 intermingled-strain flocks, each containing 36 pullets of each strain, will be used to determine the importance of social inertia in modifying the potential change in dominance status of the two strains. An experiment will be conducted to learn whether low social status depresses fitness of females of the strain which is initially lower in dominance ability, but later shows greater dominance potential. This will be tested by keeping the two strains in three distinct environments. Each strain will be represented by 40 females in each of four flocks of their own kind, by 40 in each of four intermingled flocks (containing both strains), and by 40 individually housed pullets in each of four rows of cages. Records on weight changes, survival, and reproductive traits (sexual maturity, ovulation rates, etc.) will be collected from adolescence into full maturity. BIBLIOGRAPHIC REFERENCES: Bhagwat, A.L. and J.V. Craig, 1975. Fertility from natural matings influenced by social and physical environments in multiple-bird cages. Poultry Sci. 54:222-227. Al-Rawi, B. and J.V. Craig, 1976. Agonistic behavior of caged chickens related to group size and area per bird. Appl. Anim. Ethol. 2: in press.